Ординатура / Офтальмология / Английские материалы / Pediatric Ophthalmology Current Thought and A Practical Guide_Wilson, Saunders, Trivedi_2008

Contents

20.1Epidemiology, Etiology, and Natural

History  . . . . . . . . . . . . . .   276

20.2Conservative Management  . . . . . . .   276

20.3Surgical Management  . . . . . . . . .   277

20.3.1Simple Probing  . . . . . . . . . . .   277

20.3.2Older Children and Children with Persistent

20.4.2Trisomy 21  . . . . . . . . . . . . .   281

Core Messages

•Nasolacrimal duct obstruction (NLDO) is one of the most common abnormalities in pediatric ophthalmology.

•NLD often resolves spontaneously.

•The symptom that is most useful in distinguishing NLDO from other causes of epiphora is the lack of photophobia.

•In-office probing of younger patients with

NLDO and operating room probing of older patients are acceptable treatments.

•Recognition of different types of NLDO is useful in guiding management:

–Most NLDO is due to membranous obstruction of the distal NLD and is relieved with simple NLD probing.

–Some children with NLDO have diffuse stenosis of the distal NLD, which may require more than simple probing to treat effectively (either balloon catheter dilation or stents).

–A small number of children with NLDO (particularly infants with mucoceles) have cysts or other abnormalities of the distal NLDO.

•Nasal endoscopy is a useful adjunct to treatment of children with complicated NLDO.

20.1Epidemiology, Etiology, and Natural History

Nasolacrimal obstruction (NLDO) is one of the most common problems encountered in pediatric ophthalmology, affecting approximately 6% of newborns [10]. The tears are produced in the lacrimal gland, flow across the eye to the lacrimal puncta, travel through the lacrimal sac and duct, and empty into the nares beneath the inferior turbinate. Embryologically, the distal lacrimal system develops from a solid sheet of ectodermal tissue that projects into the nasolacrimal groove between the frontonasal and lacrimal prominences in the 42-day-old embryo [4, 33]. Canalization of this tissue, which begins on day 60, results in formation of the lacrimal sac and nasolacrimal duct. The most common site of obstruction in NLDO is at the valve of Hasner, where the nasolacrimal ducts enter the nares. It usually results from incomplete canalization, rather than acquired obstruction, of the distal duct.

Two primary signs result from NLDO. The first sign is epiphora. Because the tears are unable to pass through the duct, they back up (in similar fashion to a clogged pipe) through the lacrimal system to the tear lake on the eyelid. Marked blockage results in frank epiphora, with tears spilling spontaneously onto the cheeks. This may appear as if the infant is crying. Milder blockage may produce an increased tear lake (which gives the appearance that the infant is about to start crying) with intermittent epiphora. The epiphora is usually exacerbated by conditions that stimulate tear production, such as cold weather or brisk winds. The second sign is chronic discharge and periocular crusting. This results from bacterial infection of the lacrimal sac. Bacteria from normal flora are present in the tears, but they usually do not cause infection because they are rinsed through the lacrimal system into the nares. Patients with NLDO have stasis of tears in the lacrimal sac, producing an environment conducive to bacterial growth. The typical infection has the appearance of a low-grade, chronic dacryocystitis. Both epiphora and dacryocystitis are exacerbated by upper respiratory infections, due to swelling of the nasal mucosa that worsens the obstruction of the distal duct. Except for newborns with nasolacrimal duct cysts (see below), affected patients do not have swelling or erythema overlying the lacrimal sac.

If the NLDO is marked, patients may develop erythema and maceration of the skin around the eyes.

Interestingly, most infants with NLDO do not appear to be particularly bothered by their disorder.

With the exception of patients who have skin irritation due to marked obstruction, parents usually report that their affected infants only intermittently rub their eyes. The history is important, because if the parents describe significant photophobia, one should look for other etiologies of epiphora. Corneal abnormalities in particular may cause increased tear production. Glaucoma is the most important entity that may be mistaken as NLDO by primary care physicians, who may attribute the epiphora that occurs in glaucoma to NLDO. Glaucoma is usually easily ruled out by an ophthalmologic examination that includes evaluation of corneal size and clarity, measurement of intraocular pressure, and examination of the optic nerves.Another disorder in the differential diagnosis of NLDO, particularly in Asian children, is epiblepharon with corneal irritation due to misdirected eyelashes. Children with this condition often produce excess tears, and may also have a mucoid discharge; therefore, inspection of the lid margins should be included in the evaluation of children with suspected NLDO.

The natural history of NLDO is one of spontaneous resolution. The symptoms usually begin within the first few weeks of life, and most infants improve within the first few months. This continues during the first 9−12 months of life, with resolution of symptoms in approximately 90% of infants [29].At around 9−12 months of age, however, most studies show that the rate of spontaneous improvement decreases [27].

20.2 Conservative Management

Because most infants with NLDO spontaneously improve, the initial treatment should be conservative. Most primary care physicians are familiar with NLDO, and the initial treatment is done under their direction. Infants with mild symptoms often require no treatment at all. If the symptoms are more significant, treatment options include nasolacrimal massage, topical antibiotics, or both.

If topical antibiotics are used, it is important that parents understand that the antibiotics will not cure the obstruction, and that it is common for symptoms

to recur when the antibiotics are stopped. Antibiotics may be used intermittently to decrease ocular crusting and discharge, until either the obstruction spontaneously resolves or the child undergoes surgery.

The concept behind lacrimal massage is that compression of the tear sac causes fluid to be forced through the lacrimal duct, which may cause the obstruction to open by hydraulic pressure [6]. Although commonly recommended, the effectiveness of lacrimal sac massage has never been proven. This is because the natural history of NLDO is one of spontaneous improvement, so that any intervention performed early in the course of disease could mistakenly be interpreted as being beneficial; however, there are some studies that strongly suggest that lacrimal massage is beneficial [16, 35].

If lacrimal massage is recommended, it is important to demonstrate the proper technique to the patient’s caregivers. Because the lacrimal duct is mostly covered by bone, the only access to the system is at the site of the lacrimal sac beneath the medial canthus. One can demonstrate this to parents by having them place their fingers at the inside corner of the eyelid.

The medial canthus can be palpated, and feels like a small BB beneath the skin. Gentle pressure with a finger at this site causes compression of the lacrimal sac, while simultaneously obstructing the canaliculi, giving the desired effect.

20.3 Surgical Management

20.3.1 Simple Probing

If NLDO does not spontaneously resolve, patients may require a surgical procedure to relieve the obstruction. There are two main approaches to this condition. Some ophthalmologists prefer to perform

NLDP on awake infants in the office. This may be performed as early as 1 month of age, but usually at

4−6 months of age [34]. The main advantages of this approach are: (1) general anesthesia is avoided; and

(2)the problem is resolved at a younger age. The primary disadvantages are: (1) the procedure is uncomfortable; (2) there is an increased risk of creating a false passage in an awake infant who is moving; and

(3)the procedure is performed on some infants who would spontaneously improve with time.

The second approach is to wait until the children are older (9−12 months of age) and perform the procedure in the operating room under general anesthesia. The main advantages of this approach are: (1) a number of children will improve spontaneously by waiting until a older age, thus avoiding the need for surgery; (2) the operating room is a more controlled environment, the patient is not moving, and additional procedures (e.g., endoscopy, stent placement) can be performed if necessary; and (3) pain control. The primary disadvantages are: (1) the symptoms persist longer; and (2) the risk of general anesthesia. The overall success of NLDP is usually very high

(>90% in my experience) for both in-office and operating room probing. Given the relative advantages and disadvantages discussed above, neither approach can clearly be considered superior to the other [14, 17].

As the debate between in-office and operating room probing demonstrates, the high success rate for infant lacrimal surgery in general makes it difficult to scientifically establish an optimal treatment paradigm. Statistically, when two different treatments are very effective, large numbers of patients are necessary to establish one as statistically better than the other. In practical terms, such studies are probably not necessary, because NLDO is usually successfully treated regardless of which procedure is used. Given that NLDO is not a sight-threatening problem, and the cost of a large-scale, multi-center, prospective trial of different treatments would likely be prohibitively expensive, it is unlikely that such studies will be performed. The Pediatric Eye Disease Investigator Group has utilized an alternative approach, which has some of the merits of a large-scale study but at considerably less expense. In these studies, a large number of individuals each contribute small numbers of patients to a common data collection center. This has proved very successful in the study of amblyopia [28, 37], and similar information may be obtained from this group by studying NLDO. For the present, individual decisions regarding which method of treatment to select will be based on factors such as personal experience, local practices, the availability and safety of pediatric anesthesia, and family preferences.

In addition to probing alone, some authors have advocated placement of stents in all children at the time of initial NLDP, reporting a success rate of 96%

with this procedure [8]. Although this success rate is very high, in the author’s opinion it does not justify adopting routine stent placement in all children with

NLDO. If one assumes that approximately 90% of patients are successfully treated with NLDP alone, then this practice would result in 90 children out of 100 receiving stents unnecessarily in order to successfully treat the six children who would have required stents. It is arguable as to whether the benefit outweighs the potential risks, and more intense follow-up is required for patients who have stents placed [30].

20.3.2Older Children and Children with Persistent Symptoms After Initial Probing

In the past, there has been some debate regarding the efficacy of NLDP in children who present for treatment at an older age (most commonly defined as age

18 months and older). Some studies suggest that the success rate of probing decreases as patients grow older [15, 24, 27]. Other studies report success rates

with simple probing in older children that are nearly equal to those performed at a younger age [18, 31].

The practical implication of this debate involved the treatment of older children. If the success rate of surgery was less, then most authors advocated additional treatment (typically stent placement) in order to increase the rate of successful outcomes. If there were no difference in success, then stents would be unnecessary.

The likely answer to this controversy involves the recognition that there is more than one type of nasolacrimal obstruction [11, 18, 19]. The most common type, simple membranous obstruction of the distal valve of Hasner (Fig. 20.1), is treated with a high success rate with simple nasolacrimal probing, regardless of whether the probing is performed at an early age or an older age. The second type involves diffuse stenosis that extends along the distal nasolacrimal duct (Fig. 20.2). Studies that recognize this distinction provide evidence that simple NLD probing has a lower success rate in this group [11, 13, 18, 19].

The different types of obstruction can be recognized intraoperatively based on palpation of the nasolacrimal system as the probe is passed into the distal

Fig. 20.1  Typical membranous obstruction at distal valve of Hasner (arrow). (From [19])

Fig. 20.2  Diffuse stenosis extending along distal nasal lacrimal duct (arrow). (From [19])

than fluctuant. If a mass is present in the expected location below the medial canthus, and particularly if there are symptoms of epiphora and/or dacryocystitis, imaging studies are usually not necessary to verify the diagnosis.

In addition to the swelling that is noted at or shortly after birth, another important distinction between mucoceles and typical NLDO is the presence of acute dacryocystitis. Typical NLDO is characterized by an indolent, recurrent, low-grade chronic dacryocystitis, not accompanied by visible swelling overlying the lacrimal sac. In contrast, if a mucocele becomes infected, the area becomes inflamed and erythematous

(Fig. 20.4). Purulent material is often not spontaneously noted, due to the one-way valve effect of the valves of Rosenmuller, but frank pus may sometimes be expressed with pressure over the sac.

A third important distinction is the nearly universal presence of a nasolacrimal duct cyst in children with

mucoceles (Fig. 20.5). The etiology of these cysts presents the “chicken-and-the-egg” question. Does the cyst, with its marked obstruction, cause the mucocele to develop, or does the presence of the mucocele cause the cyst to develop? A plausible etiology is that two conditions must be present for cysts to form: (1) Rosenmuller valves that have a strong one-way valve effect, creating increased pressure within the lacrimal sac; and (2) a more-resistant-than-normal membrane at the distal valve of Hasner, which expands to form a cyst.

In addition to the lacrimal symptoms, nasolacrimal cysts may cause breathing problems if they are large enough to obstruct the nasal passages [7, 22].

Subtle symptoms of this may be raspy breathing.

Moresignificantsymptomsincludedifficultyfeeding.

This may occur because infants are obligatory nasal breathers. If their mouths are occluded with bottles or nipples and cysts obstruct their nares, they may be

unable to breathe. The most severe symptom is frank respiratory distress, in which case urgent treatment is indicated.

The initial treatment of non-infected mucoceles is conservative, typically with warm compresses, gentle massage to the swollen area, and topical antibiotics. If the sac becomes infected, surgical treatment is indicated. These infants have more severe infections than those in typical NLDO. Because these infections occur within the first few weeks of life, when infants have relatively immature immune systems, there is an increased risk of systemic infection; therefore, systemic antibiotics should be used if acute dacryocystitis develops.

Because mucoceles are uncommon, it is not possible to discern an optimal treatment based on the literature. The author’s approach is to treat non-infected mucoceles conservatively for the first 1−2 weeks of life [32]. If the mucocele does not resolve by this time, if the mucocele becomes infected and acute dacryocystitis develops, or if the patient has respiratory distress, then surgery is performed. Intrave-

nous antibiotics are given intraoperatively due to the young age and more severe infections. The NLD probing is performed in the same manner performed in older children. Nasal endoscopy is performed routinely because of a relatively high rate of recurrence with probing alone [25], particularly if dacryocystitis is present [2].Anasolacrimal cyst has been present in every case treated by the author (Fig. 20.6) [20]. The cyst is removed with an alligator forceps under endoscopic visualization. Frequently, frank pus comes out of the sac once it is penetrated (Fig. 20.7), and this is removed with suction. After the cyst is removed, the stent can be clearly visualized in its normal location. The success rate for this procedure has been

95% [20].

20.4.2 Trisomy 21

Children with trisomy 21 have a number of ocular problems that occur with increased frequency, one of

Fig. 20.6  Nasal lacrimal duct cyst beneath inferior turbinate in infant with mucocele. (From

[39])

Fig. 20.7  Purulent material present within cyst opened with alligator forceps. (From [39])

which is NLDO. In general, the success rate for treating such patients is less than in other children [5, 21].

There are probably several reasons for this. Firstly, children with trisomy 21 have a higher incidence of blepharitis, which may be difficult to distinguish from

NLDO due to the common symptoms of increased tearing and mucoid discharge. Secondly, one of the systemic features of trisomy 21 is midfacial hypoplasia, which includes the bony structures that surround the nasolacrimal system, making anatomic abnormalities more likely. The third reason is hypotonia, which is a systemic manifestation of trisomy 21. This is likely the most important reason for decreased success. Proper function of the lacrimal system relies on a pump mechanism generated by the orbicularis muscles [12, 26]. The hypotonia in trisomy 21 patients decreases the effectiveness of this pump, creating relative stasis of fluid within the lacrimal sac, which increases the likelihood of infection. Children with trisomy 21 may also have typical NLDO, which can be successfully treated with NLDP; however, NLDP does not improve the lacrimal stasis and, therefore, symptoms are more likely to persist.

Because of these factors, the author’s approach to children with trisomy 21 and NDLO is now similar to that of older children with NLDO. A previous study was performed utilizing BCD in all such patients, [21] but this is no longer used routinely. A regular probing is performed, as well as endoscopy. BCD is performed if diffuse stenosis is present or if fluid irrigates poorly following the probing. There is a higher incidence of palpating minimal or no obstruction during probing in children with trisomy 21, which supports the contention that hypotonia contributes to the etiology of NLDO in these patients.

There is a higher rate of NLDP failure in patients with trisomy 21. Even when the condition improves following surgery, patients often have some residual symptoms. Despite repeated procedures, it is often difficult to completely eradicate all of these symptoms, due to the factors discussed above. Preoperative counseling regarding the prognosis for NLDP in children with trisomy 21 is important. If the symptoms improve after surgery, the author’s usual practice is to accept minor residual symptoms, and not to perform repeat surgery with the often-elusive goal of achieving complete resolution of symptoms.

20.4.3Punctal and Canalicular Abnormalities

Other anatomic abnormalities of the nasolacrimal system may produce symptoms that are similar to those of NLDO. One of these symptoms is absence or maldevelopment of the puncta or canaliculi. Children with this problem develop epiphora, because the tear lake does not have access to the lacrimal system.

An important historical and examination finding in these patients is the absence of dacryocystitis. The lacrimal sac does not become infected in these patients, because bacteria cannot gain access to the sac itself.

When examining patients with symptoms of

NLDO, it is important to inspect the lacrimal puncta for evidence of maldevelopment. It is relatively easy to inspect the lower puncta by gently everting the lower lid in the office. Evaluation of the upper puncta is more difficult and may not be possible in an uncooperative infant. Preoperative recognition of punctal abnormalities is helpful for parental counseling and operative planning. The type of abnormality ranges from a simple membranous obstruction overlying the puncta (in which case the puncta itself may look normal), to complete agenesis of the canaliculus (in which case the eyelid margin may be completely flat, without any discernible dimple in the area where the puncta is normally located (Fig. 20.8).

The true incidence of punctal and canalicular maldevelopment is unknown. This is because if only one of the upper or lower canaliculi is abnormal, the

Fig. 20.8  Congenital absence of lacrimal puncta.

(From [40])

other canaliculus may provide enough drainage that epiphora does not develop. This abnormality may therefore be more common than is realized, because patients have no symptoms and are therefore never examined.

Treatment of membranous punctal obstruction is straightforward, even if the membrane is not recognized until the patient is in the operating room. Puncturing the membrane with a punctal dilator usually successfully treats the problem. Treatment of true canalicular agenesis is more difficult. If there is no visible punctal tissue, a linear incision can be made through the lid margin between the site where the puncta normally is located and the medial canthus, looking for canalicular tissue. This is often unsuccessful [23]. Patients with canalicular agenesis and chronic epiphora may require Jones tube placement to improve their symptoms, and this is often deferred until an older age [23, 38].

Many patients who present with symptoms of NLDO and who are found to have punctal and canalicular abnormalities also have typical membranous obstruction of the distal NLD [23]. This is particularly true if the patients have dacryocystitis, because this indicates that there is a connection between the eyelid and the lacrimal sac. If punctal agenesis is present on only the upper or lower eyelid, a simple probing through the patent puncta has a high rate of

success in such patients, and is recommended as an initial treatment before considering more extensive canalicular surgery.

20.4.4 Lacrimal Fistualae

Another unusual anatomic abnormality of the lacrimal system is a lacrimal fistula. In this disorder, an accessory tract develops between the lacrimal sac and the skin overlying the medial canthus. This may be recognized as a small dimple in the skin at this site

(Fig. 20.9), but a fold of skin sometimes obscures this. The opening is so small that it may not be brought to medical attention in the absence of symptoms. If the fistula is patent, patients may develop epiphora from the site. Occasionally the fistula is not recognized until during surgery for NLDP, at which time fluid emerges from the tract during irrigation of the lacrimal system.

No treatment is necessary if patients are asymptomatic. Surgery is indicated if bothersome epiphora or an infected fistula tract is present. There is a high rate of recurrence with simple cauterization of the tract. Successful treatment usually requires excision of the tract and ligation of the fistula where it joins the lacrimal sac (Fig. 20.10) [3, 36].

Take Home Pearls

•Spending a few minutes explaining the etiology and management of NLDO to parents of infants is useful. They

should understand that topical antibiotics will not cure the obstruction, and that

it is normal for symptoms to recur when antibiotics are discontinued.

•Attention to palpation during probing may help guide surgical decisions:

–The presence of diffuse stenosis of the distal duct may require more than simple probing to cure (either balloon catheter dilation or stent placement).

–The failure to palpate metal-on-metal contact between a probe in the NLD and a probe in the nares may indicate the presence of a nasolacrimal duct cyst or other anatomic abnormality.

•It is often difficult to eradicate symptoms of NLDO in children with trisomy-21.

Asignificant improvement in symptoms may be an acceptable outcome.

•Infants with mucoceles almost always have nasolacrimal duct cysts. Removal of these cysts may increase the success rate of surgery.

•Children with punctal agenesis of one eyelid and symptoms of NLDO often improve with simple NLDP through the eyelid with the patent canaliculus.

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